Method of preparing tetrachlorothiophene



United States Patent (Mi 3,350,410 METHOD OF PREPARING TETRA- CHLOROTHIOPHENE Roland Henry Goshorn, Fort Washington, and Thomas Edward Deger, Ambler, Pa., assignors to Pennsalt Chemicals Corporation, Philadelphia, Pa., 11 corporation of Pennsylvania No Drawing. Filed July 7, 1965, Ser. No. 470,243 11 Claims. (Cl. 260-3325) ABSTRACT OF THE DISCLOSURE Tetrachlorothiophene is prepared by reacting sulfur, e.g., at from about 150 C. to about 350 C., with trichloroethylene or tetrachloroethylene.

chloroethylene or where R is hydrogen or chlorine.

Tetrachlorothiophene is a well known tures for 7 to 5.0 hours.

The present invention provides a simple, economical process for preparing tetrachlorothiophene using inexstarting materials. In accordance with this invention, sulfur is because higher yields of tetrachlorothiophene are obtained therewith. The tetrachlorothiophene product is recovered from the reaction mixture by suitable, Well-known separation techniques as hereinafter described. The reaction may be depicted by the following equation wherein trichloroethylene and sulfur are the reactants.

1 1 S S HCI ifi 2 o :00 H 2 a 010 /oo1 In addition to the HCl, other by-products are formed in Patented Oct. 31, 1967 ice 2. the reaction including sulfur monochloride and other forms of sulfur chlorides.

The molar ratio of the may be in the range of from about preferred.

The reaction embodied in this invention is carried out at elevated temperatures, generally within the range of about. 150 to about 350 may be used as a diluent, such as diphenyl (B.P. 254 C.), naphthalene (B.P. 218 C.), the methyl naphthalenes (B.P. 241245 C.), acenaphthalene (B.P. 278 C.), and the like. Employing a diluent facilitates operations at the lower pressures but renders product recovery more difficult.

period of reaction is not critical and may extend up to about hours, although the reaction usually is completed in from about 2 to 6 hours. In another embodiment of the process, the chloroethylene can be fed incrementally or in a slow, continuous metered stream onto the surface of molten sulfur where it reacts at the reaction disclosed Examples 1-4 In each of a series of four experiments herein described, measured ution of sodium hydroxide. After a suitable reaction period, evidenced by a cessation of HCl evolution, the reaction mass is cooled, removed from the autoclave, and then subjected to a simple distillation using a column packed with glass helices. The distillate product E am I 11 is analyzed by infrared spectroscopy techniques. The data x p e and results of Examples 1-4 are summarized in the 101- A flask equipped with a reflux condenser and stirrer is lowing Table A. charged with one gram-mole of trichloroethylene, 1.5

TABTJE A Charge Reaction conditions Recovery f Trichloro- Tetrachloro- Percentyield, ethylene, Sulfur, Temp., Pressure, Time, thiophene, based on moles moles C. p.s.i.g. hours moles trichloroethylene X 1 That theoretically could react with all the sulfur charged. 2 Tetrachlorothiophene identified in product but yield not in measured.

Example 5 gram-moles of sulfur and, as a reaction diluent, 132 grams of diphenyl. The mixture is stirred for 16 hours at 200- g l of mole of trlchloifethylene are 220 C. Tetrachlorothiophene, in an amount equal to 6 large mm a stanllxess steel autfclave W Sealed 5% of the theoretical yield based on the trichloroethylene er vaclmm and Gated at 72 P The charged, is isolated from the reaction mixture. autoclave is cooled and the oily reaction mass is treated We claim, four times Wlth separatehportions ofhdiethylether in an L A method of preparing tetracmomthiophene which amount approximately e Slze of t e Eamon mass comprises reacting sulfur with a chloroethylene of the extract the tetrachlorothiophene therefrom. The ether 1s formula removed from the extract by distillation and the remaining brown residue is treated with hot water to remove sulfur 3O 01 c1 chlorides. The residue is steam distilled to strip off residual 0: trichloroethylene. After the water is removed by decanta- (1; 1 tion, 0.02 mole of tetrachlorothiophene is recovered from 1 R the residue by vacuum distillation and purified by vacuum sublimation, equivalent to a yield of 10%. where R is hydrogen or chlorine.

2. The method of claim 1 wherein the chloroethylene is Examples 6-9 trichloroethylene.

3. A method of preparing tetrachlorothiophene which In each of a series of four experiments herein described, comprises contacting sulfur with a chloroethylene 0f the measured amounts of tetrachloroethylene and sulfur are 40 formula sealed in vacuo into a stainless steel autoclave and reacted at elevated temperatures as described hereinbelow for C1 90 hours. The maximum pressure during reaction is about 3;: 270 p.s.i.g. The autoclave is cooled and the reaction products, a brown liquid containing small amounts of slushy solid, is treated with hot water to remove sulfur halides. Residual tetrachloroethylene is taken off by steam distil- Where R 15 y g or chlorll'le, at a temperature Within lation and the water is separated from the residue by t e ng f a ut 150 to about 350 C. and at a pressure decantation. Tetrachlorothiophene and traces of hexawithin the range of about 1 to about atmospheres, the hloro tha a ov red f m th idu by v um molar ratio of sulfur to the chloroethylene being within distillation and the tetrachlorothiophene is purified by 50 th r ng of about 0.221 to about 12:1. sublimation. The data and results are summarized in 4. The method of claim 3 wherein the chloroethylene Table B. is trichloroethylene.

5. The method of claim 3 wherein the chloroethylene TABLE B 1s tetrachloroethylene.

6. The method of claim 3 wherein the sulfur and chlo- Oharge roethylene are contacted in the presence of a high boiling Yield of tetrachlororeaction diluent. was... an... teats, stalemate method r preparing erachlowthiophene which ethylene, moles percent comprises contacting sulfur with a chloroethylene of the moles 6O formula 5 0.3 1.2 250 15 c1 01 7 0.3 1.2 230 10 J I 8 at a: a in it Example 10 where R is hydrogen or chlorine, at a temperature within the range of about 200 to about 300 C. and at a pres- Trichloroethylene is fed drop-wise onto the surface sure within the range of about 10 to 40 atmospheres, the

of molten sulfur in a flask at a temperature of about 7 molar ratio of sulfur to the chloroethylene being within 250260 C. The reaction is at atmospheric pressure. the range of about 0.521 to about 5:1.

Approximately 1% of the trichloroethylene is converted 8. The method of claim 7 wherein the chloroethylene to tetrachlorothiophene. The major portion of the triis trichloroethylene.

chloroethylene flashes off, is condensed and recovered for 9. The method of claim 7 wherein the chloroethylene recycle. 7 is tetrachloroethylene.

6 10. The method of preparing tetrachlorothiophene References Cited which comprises feeding a chloroethylene of the formula UNITED STATES PATENTS 0101 2,410,401 10/1946 Coffman 260 329 (ll=gl 5 3,043,887 7/1962 Becke 260650 g 3,149,124 9/1964 Krespan 26O-332.2 where R is hydrogen or chlorine, onto the surface of 3278552 10/1966 Geenng 260 330'5 molten sulfur. P

11. The method of claim 10 wherein the chloroethylene WALTER MODANCE nmary Exammer' is trichloroethylene, 10 C. M. SHURKO, Assistant Examiner. 

1. A METHOD OF PREPARING TETRACHLOROTHIOPHENE WHICH COMPRISES REACTING SULFUR WITH A CHLOROETHYLENE OF THE FORMULA 